Bird grape battle rolls on
A combination of bird control methods is most effective at scaring hungry birds away from grape crops, say Marlborough grape growers.
About 30 viticulturists and grape growers checked out the latest developments in bird control at the Fruitfed Supplies' bird and pest control day at Yealands' Grovetown vineyard on Friday. From now until the end of harvest - mid to late April - they will be armed with nets, shotguns, air guns, sound and visual scarers to protect their crops from flocks of birds.
Marshlands grape grower Greg Neal thought a new aerosol bird repellent would be a useful addition to his arsenal of bird-scaring tools.
The gas-powered hand-held machine would be ideal to use around places where loud noises were not welcomed, such as close to residential properties, he said.
"Different spots will have different pressures," he said.
Mr Neal has already netted his pinot noir blocks but prefers to use gas guns for sauvignon blanc. However, it did not pay to get too hung up on bird control, he said.
"You have to be careful because you can drive yourself nuts trying to get every last bird."
Although it was difficult to gauge how much damage birds caused, the outer edges of vineyards, and rows close to trees appeared to be the worst hit, he said.
Effects of bird damage included a reduced crop and increased risk of botrytis and disease.
Mr Neal was most interested in the aerosol Fog Force repellent, a hand-held smoke blower which spread a repellent which was 40 per cent methyl anthranilate and 60 per cent soy oil. This caused a brief burning sensation in birds' eyes, mouths and beaks.
Fog Force was available last year but there were concerns about residue being left on fruit. However, after extensive testing no harmful traces were found.
Fruitfed sales manager Richard Rutherford said birds would cause problems from now until the end of harvest, as fruit sugar levels increased and grapes started to change colour.
The Marlborough Express